Benitez is the third lawyer to represent Tahmooressi since he says he accidentally crossed the U.S.-Mexican border with registered weapons in his truck in the early-morning hours of April 1. The weapons are illegal in Mexico, and he has been jailed since.

A new court date has been set for July 9, Fox News reported.

Tahmooressi says he made a wrong turn and was funneled into a lane taking him to the Mexican border, but was unable to turn around before he was on Mexican soil. He said he told Mexican border agents about the weapons, but was arrested and sent to prison.

Benitez told Van Sustern that federal prosecutors in Mexico have 48 hours to decide whether to prosecute a case, and that during that time defendants have a right to counsel and can submit evidence in an attempt to have charges dropped.

Though Tahmooressi was given a lawyer, an interpreter and access to the U.S. Consulate, his attorney did not make efforts to submit evidence within the 48-hour time limit.

"I really don't know the reason why this wasn't done," Benitez said.

Tahmooressi's case has become a cause célèbre, with Van Susteren leading the charge to have the Afghanistan war veteran, who suffers from PTSD, released. The Veterans of Foreign Wars urged a boycott of Mexico until he is freed.

Benitez would not criticize Tahmooressi's previous attorneys or say whether he would have done things differently, but said his own style is to be more aggressive for his clients.

"I think that once the specifics of those facts come to light we will have a good shot at proving there is no malicious intent in his conduct," he said.

He also explained that though Mexico's legal system differs from that of the United States, the accused still has the presumption of innocence.

"Andrew is innocent until the state proves that he's not," Benitez said. "It might not seem that way, and the reason for that is that firearms offenses here sometimes are not afforded bail."

He added, however, "It will be upon the state to prove that he's guilty. We don't have to prove anything."